1. Field of the Invention
The present invention relates to open top container filling and closing methods and apparatus. More particularly, the present invention relates to a method and apparatus for preparing a filled can for closing or "lidding" by cutting and removal of excess product from the can flange area and cleaning the same. The present invention has particular application in the food canning and processing industries because of the need for obtaining perfect seams for proper sealing. It will be understood, however, that the invention has a broader application in such areas as the packing of non-food stuffs where can sealing is a problem because of the nature of the product being packed.
2. The Prior Art
Particular care must be taken especially in the food canning industry to obtain a perfect seal in order to prevent spoilage of the food material. In canning operations utilizing metal cans this usually dictates the absence of any food particles or residue around the top edge or flange of the filled can in order to obtain a perfect seam to seal all possible air leaks. In the typical food canning operation, after a can is filled with a food product and liquid, it is delivered to a head spacer. Head space is obtained by inserting a plunger into the can to displace excess liquid and to compress the product prior to lidding. In the canning of meats and fish the filling operation may be performed by a plunger which is used to insert a block of product into the can in such a manner as to leave sufficient head space without the need for an independent head spacing operation. In either case, a lid is then sealed to the can by the formation of a crimped seam between the lid and a small outwardly flaring flange about the upper edge of the can. This seam must be tight enough to prevent contamination of the contents by bacteria or the like, or a serious health hazard will result. Although the packing of non-food products may not present health hazards, the formation of a perfect seal may be necessary to prevent spoilage or deterioration of the product.
During the filling of the can or the formation of a head space involving the use of a plunger, food particles sometimes protrude from or splash onto the exterior of the can and cling to the flange area. With some types of food, such as meats containing tough tissue or bone, the problem becomes quite severe. Food debris on the flange can makes a tight crimp between the flange and lid impossible, and thus interferes with proper sealing of the can. Although it is common to wash the can side preparatory to lidding and labeling, this washing operation is not effective to insure removal of food debris and is outside of the subject matter of this invention. There have been developed certain types of mechanical cutters for trimming the debris, however, these mechanical methods have not proven to be a satisfactory solution to the problem. One example of mechanical trimming apparatus is disclosed in U.S. Pat. No. 2,444,502, issued July 6, 1948 to W. C. Fromer. Consequently, the present practice in most canning operations is to inspect each can and manually remove debris and repair each defectively filled can by hand or to pull the can from the line. Because of high labor costs, this is an expensive operation and one which does not eliminate the possibility of a defective seam being overlooked and going unrepaired.
The food canning industry in particular, therefore, has a clear need for a device and method to prevent defective can seams caused by particles of food product lying along the flange area of the can. A device and method is thus needed which will alleviate the necessity for a labor intensive procedure and will remove the cause of defective seaming at the outset.